Thermally stable derivatives of propylenepolyamines as protective additives for lubricating oils used in compressors handling hydrogen sulfide-containing gas

In the transmission of natural, associated, and petroleum gases containing hydrogen sulfide, carbon dioxide, water, and other corrosive impurities, problems are created by the saturation of the compressor lubricating oil with these impurities and failure of components of the lubricating and sealing system. Hydrogen sulfide is distinguished by the greatest affinity for oil and the highest corrosivity. Its solubility in oils may be as high as 10 g/liter under standard conditions. In the work reported here, we investigated the protective properties of salts and amides based on higher aliphatic, alkylaromatic, and unsaturated carboxylic acids with certain substituted propylenepolyamines. In synthesizing the additives, we used the following: a commercial C{sub 17} - C{sub 20} fraction of synthetic fatty acids (SFA): C{sub 25+} still bottoms; technical alkyl (C{sub 16} - C {sub 18}) salicylic acids; and oleic acid. From these materials, we obtained salts and amides of N,N-dimethylpropanediamine, N-benzylpropanediamine, N-cyanoethylpropanediamine, N,N,N`,N`-tetramethyldipropylenetriamine, and N,N-dimethyldipropylenetriamine.